There is an old children’s song comparing the wise man and the foolish man. Ah, but it might as well be talking about a Tiny House foundation! The song goes something like this: the Foolish man built his house upon the sand . . . and the house came tumbling down. . . . The Wise man built his house upon a rock . . . and the house on the rock stood still. – Or something like that. (If you know the words and the tune, ya gotta sing it!)
It is an interesting metaphor when taken literally, but it takes on a slightly different meaning when thinking about the foundation for a Tiny House.
Yes, for a Tiny House, the trailer is indeed the foundation. You build a house on a foundation – and Tiny Houses are no different. The tiny house foundation IS the trailer, so it has got to stand up to the environment – which includes not only the wind loads, snow loads, and regular wear and tear, but also – for a tiny house -rolling down the highway (over potholes, and other road debris).
Certainly, the job of the tiny house foundation has an expanded role compared to the job of a regular house foundation. So, we will treat it better!
Engineering Tiny House Trailers
At Synthesis, we get calls fairly frequently from people asking about trailers for a tiny house. The questions vary, of course, but the essence is often: “What can I get away with for a trailer?” Not so unlike sand, an insufficient trailer will not make a solid foundation (or stable platform) to build your house on. Tiny houses definitely need a purpose-built trailer. And, we can learn a lot from the Old Time Tiny Houses with their unique mobile platform.
My Questions In Response To These Inquiries Are: First, How long do you want your tiny house to last? Then, Second, How much trouble do you want to deal with?
The answers to these 2 questions (never asked directly) drive the trailer choices for your tiny house trailer design.
The Tiny House Trailer has to deal with a lot of things that other trailers do not, so the design must consider these additional conditions. You can read about the engineering and design process for out Tiny House Foundation Trailers. The article explains many of the functional considerations that go into creating the trailer design. That article explains how we make decisions, and how we research things before we dive in. You can read a similar discussion about the process in designing our Deck-Over style trailers, and research for our Car Hauler Trailers.
That leaves only the matters of trailer size (to accommodate what kind of house), and capacity (how much will the house weigh?). Weight we will discuss below, but size, that can be a Tiny House Quandary so we will leave that to you.
Tiny House Foundation Size
What is the size of “Tiny”? – I will leave that for you to ponder.
The concepts of living tiny also mean living with an efficient use of space. To find out what will work for you, we strongly recommend spending some time visiting tiny homes to gather ideas for what will work for you.
To help, we offer several trailer “foundation” sizes. The standard width is 8.5 feet (102 inches) max width. That is what the law says (in most places in the USA and Canada). That leaves a choice of length, and we have you covered for the standard lengths.
On the other hand, we also offer a couple tiny house foundation trailers that are extra wide – if you are more comfortable with a little more space. These will require a permit to pull on public roads. However, if you do not plan to move it much, the extra width can be nice. Here is some additional reading on Wide foundation trailers.
Tiny House Weight / Trailer Load Capacity
Weight estimates are a tough one to grapple with. How much does a tiny house weigh? So many variables, and so much to consider. Will it be made of lumber? Or metal? Thick walls for cold weather? Does it have freshwater or black water storage tanks? How many and what size of batteries? Appliances? Solar panels? Electronics?
Compact is the reality and very nature of the tiny house, which means materials are tighter and denser than typical construction. Also, being roadworthy requires an extra level of sturdiness.
How much does that all weigh? Truly, it varies, and every house plan I have seen is unique, so you will need to do the math. However, from what we have seen, something in the neighborhood of 500# per linear foot is not out of the question. Some are more, some less – so do not use this number and think everything is OK. Go back to the wise man song. The wise man also considers just how much rock he needs for the house to stand on.
Take the weight information and it will point you to the right tiny house foundation capacity. You will need one that exceeds whatever you calculate as the need. We recommend exceeding it by quite a bit since things always change and it is so much better to over-design a bit, than to wish you had.
Side note, all the information, and the available Tiny House Trailer Plans are in Imperial dimensions. Read more about Metric here.
The New “Rock” To Build On
So, on that note, we are introducing the new “Rock” and the big brother. Then, there is the long one with a build choice of 30 ft or 32 ft length. Our latest DIY project is an amazing Tiny House Foundation – a trailer designed specifically for Tiny Houses. This design is really strong and reasonably easy to build, so you can make it to last (as the song says) … the Tiny House on the rock stands still.
These particular trailers are 100″ width (allowing for siding overlap and still be legal). DOT legal width limit is 8.5-ft for the USA and Canada. Other countries are similar, but look it up. Our new tiny house foundations have 20-ft or 24-ft or 30-ft or 32-ft bed lengths. Other features include a max capacity of 14,000 lbs tandems (up to 24,000 lbs for the triple), and a low deck height with an integrated floor for even more headroom.
As I speak to Tiny House creators, deck height is usually very high on the priority list, but there are trade-offs. So, these new trailers not only have a low deck height, they also have the house floor integrated into the trailer frame for even better support and to minimize the true floor height. (That gives more headroom.)
Most important to this discussion, this Tiny House trailer minimizes deflection in all conditions even with the low deck height. This is key to longevity and stability of your home. See the discussion about deflection in our previous post. These trailer frames are very strong, yet more important, they are stiff. So, if you build with care, it will make a very stable, very strong, Tiny House Foundation.
Compare this discussion on strength with some other popular opinions – though misguided – as in this YouTube Video review. Strength, yes. But stiffness is really the trailer limit for success with your tiny home.
Your Turn – The Tiny House Foundation
If the foundation is the most important thing to get “right”, one of these new “Rocks” are a great choice. DIY plans are available for 3 versions our Tiny House Foundation. Select the size you want here. (Tiny House Foundation Trailers are down the page slightly.) Then, right after payment confirmation, you can save the blueprint files directly to your computer. And, we take care of our customers, so let us know if you have trouble with the downloads.
Please do not think that these plans are the final work for your tiny house foundation. If your trailer design goals are not in perfect harmony with these plans, then customize. We encourage customization – within certain limits – so the final result is exactly what you need. That is another beauty of working with us. The plans show areas for choices and give some understanding about why you may choose one thing or another. After all, it is your tiny house, not ours, so the foundation should fit your needs.
We invite you to have a look at the plans, then let us know what you think.
Tiny House Foundation Update – 2021
We now have the Wide and the Extra Wide tiny house mobile foundations for you. From many requests, we are answering the needs you, our customers, are wanting. The 10-ft wide by 32-ft length is a fantastic size. Then, the really big (well, can we say “Large Tiny?” house) 12-ft wide by 32-ft length mobile foundation.
The larger size meets the max size recommendation guidelines as being a “tiny house” on wheels per the newer proposed regulations. (If that is important to you.)
Both of these wide trailers will require a permit to tow on the road, but if you want a little more elbow room in your tiny home, these wider tiny house foundations are certainly worth a look. (Please check the requirement for where you plan to tow the trailer, if at all, to be sure you are willing to meet the permit regulations.) Most tiny homes do not travel much, so the need for permits is usually rare. Check it out anyway so you know.
Update – 2023
By your request, we have added a few things and made a several minor changes to improve the very popular 8.5-ft x 32-ft Tiny House Trailer Plans. Check out the list of improvements in the article “Next Generation Tiny House Trailer Design Improvements“. Some of the changes are specific to this one trailer. Others will cascade across our whole line of tiny house foundation plans as we get time to do all the needed engineering analysis, then change the existing drawings. Stay tuned, we always strive to make our plans better and better.
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